Transcript Chapter 1 - The Science of Biology

Chapter 1 - The Science of
Biology
1-1 What is Science?
• Goal= investigate and understand the
natural world, to explain events, and to
use those explanations to make useful
predictions.
• Scientfiic Method
• Steps: observe to gather data
- observation= gathering data
1-1
- hypothesis= proposed explanation for a
set of observations
a. can be tested by experiment or data
b. disproved or supported by data
1-1
• Review:
1. Why is it important for you to know
about biology?
2. Why is skepticism considered a
valuable quality in a scientist?
3. What is the difference between
qualitative and quantitative data?
1-2 How Scientists Work
• Spontaneous generation- old theory that
life could come from nonliving matter
ex: meat left on counter will grow
maggots
• Francesco Redi (1668)- created new
hypothesis that flies laid eggs on the
meat which hatched maggots
– Used scientific method to create an
experiment
1-1
Designing an experiment
State the Problem
Analyze Results
Form a Hypothesis
Draw a Conclusion
Set Up a Controlled Experiment
Publish Results
Record Results
1-1
• A Controlled Experiment is an experiment
in which only one variable is changed at a
time.
- Controlled variables – kept the same
- Manipulated variable – variable that is
changed
- Responding variable – what is observed
to changed in response to manipulated
variable
1-1
Figure 1-8 Redi’s Experiment on
Spontaneous Generation (1668)
OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat.
HYPOTHESIS: Flies produce maggots.
PROCEDURE
Uncovered jars
Controlled Variables:
jars, type of meat,
location, temperature,
time
Covered jars
Several
days pass
Manipulated Variables:
gauze covering that
keeps flies away from
meat
Responding Variable:
whether maggots
appear
Maggots appear
No maggots appear
CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous
generation of maggots did not occur.
1-2
• Repeating Investigations- controlled
experiments should be reproducible
- three scientists supported Redi’s
conclusions with additional experiments:
Needham, Spallanzani, and Pasteur
1-2
Figure 1-10 Spallanzani’s
Experiment
Gravy is boiled.
Flask is
open.
Gravy is boiled.
Flask is
sealed.
Gravy is teeming
with
microorganisms.
Gravy is free of
microorganisms.
1-2
Figure 1-11 Pasteur’s
Experiment
Broth is boiled.
Broth is free of
microorganisms
for a year.
Curved neck
is removed.
Broth is
teeming with
microorganisms.
• 1864- Convinced scientists that
spontaneous generation was invalid
• Impacted industry and medical research
1-2
• Alternative experiments
- Field studies view animals in
environment
- Theory – well-tested hypothesis that
explains a broad range of observations
-ex: theory of plate tectonics
- Biogenesis – “generating from life”;
theory resulting from multiple experiments
previously discussed
1-2
• Major Discoveries in History of Biology
Detailed study of human
1543 Andreas
anatomy
Vesalius
1628 William
Harvey
1673 Anton van
Leeuwenhoek
1859 Charles
Darwin
1881 Louis Pasteur
1953 Watson &
Crick
Circulation of blood
Perfects simple microscope
to observe cells
Publishes theory of natural
selection
Develops vaccine against
anthrax
Determined structure of DNA
1-3
• Review:
1. What was the manipulated variable in
Redi’s experiment?
2. What was special about Pasteur’s
apparatus?
3. How does a hypothesis become a
theory?
If you were to make a list of characteristics
of a living thing, what would be on it?
1-3 Studying Life
• Biology- the science that seeks to
understand the living world.
• Characteristics of living things
Characteristic
Living things are made up of
units called cells.
Living things reproduce.
Living things are based on a
universal genetic code.
Examples
Many microorganisms consist of
only a single cell. Animals and
trees are multicellular.
Maple trees reproduce sexually.
A hydra can reproduce
asexually by budding.
Flies produce flies. Dogs
produce dogs.
1-3
Characteristic
Living things grow and
develop.
Living things obtain and
use materials and energy.
Living things respond to
their environment.
Living things maintain a
stable internal
environment.
Taken as a group, living
things change over time.
Examples
Flies begin life as eggs, then become
maggots, and then become adult
flies.
Plants obtain their energy from
sunlight. Animals obtain their energy
from the food they eat.
Leaves and stems of plants grow
toward light.
Despite changes in the temperature
of the environment, a robin maintains
a constant body temperature.
Plants that live in the desert survive
because they have become adapted
to the conditions of the desert.
1-3
• Important terms
-Cell- collection of living matter enclosed
in a barrier
-Sexual reproduction- two parents
-Asexual reproduction- one parent
-Metabolism- all chemical reactions in an
organism
-Stimulus- signal to which an organism
responds
-Homeostasis- process by which
organisms maintain internal conditions 1-3
• Branches of Biology
-Zoologists- study animals
-Botanists- study plants
-Paleontologists- study ancient life
-Molecular biologists – study the chemistry
of living organisms
-Population biologists – study the
interactions of animals
1-3
Figure 1-21 Levels of Organization
Biosphere The part of Earth
that contains all
ecosystems
Biosphere
Ecosystem Community and
its nonliving
surroundings
Hawk, snake, bison, prairie dog, grass, stream, rocks, air
Community Populations that
live together in a
defined area
Hawk, snake, bison, prairie dog, grass
Population Group of
organisms of one
type that live in
the same area
Bison herd
1-4
Organism
Individual living
thing
Bison
Groups of
Cells
Tissues, organs,
and organ
systems
Brain
Nervous tissue
Cells
Smallest
functional
unit of life
Groups of atoms;
smallest unit of
Molecules
most chemical
compounds
Nervous system
Nerve cell
Water
DNA
1-4
• Review:
1. Which characteristics of life does an
automobile have? Why isn’t it considered
a living thing?
2. In what context have you heard about
metabolism before today?
3. What is another type of biologist not
mentioned in the notes, and what do they
study?
Click to play “It’s Alive Part 1”
Click to play “It’s Alive part 2”
1-4 Tools and Procedures
• The METRIC system- decimal system of
measurement whose units are based on
multiples of ten
Kilo
Hecto
Deka
base
deci
centi
milli
Km
Hm
Dm
m
meter
dm
cm
mm
0.001
0.01
0.1
1
10
100
1000
1-4
Analyzing Biological Data
• tables and graphs are used to view trends
and patterns in the data
Water Released and Absorbed by Tree
Released
by Leaves
(g/h)
8 AM
1
2
10 AM
1
5
12 PM
4
12
2 PM
6
17
4 PM
9
16
6 PM
14
10
8 PM
10
3
20
Relative Rates (g/h)
Time
Absorbed
by Roots
(g/h)
Water released by leaves
15
10
5
Water absorbed by roots
0
8 AM 10 AM 12 PM 2 PM
Time
4 PM
6 PM
8 PM
1-4
Microscopes
• Light microscopes- produce magnified images
by focusing visible light rays
– Mag 1000 times
• Electron microscopes- produce magnified
images by focusing beams of electrons
– Mag 1,000,000 times but require vacuum
– Transmission electron microscopes (TEMs)shine beam of electrons through thin
specimen
– Scanning electron microscopes (SEMs)- scan
the surface of specimen with electrons to
make 3D image
1-4
• Review:
1. How many meters are in a kilometer?
2. How many centigrams are in a gram?
3. What must always be included on a
graph?
4. TEMs and SEMs require a vacuumed
environment. How does this affect the
specimen?